This invention relates to a collected toner conveying device of an electrostatic recording apparatus wherein a toner image formed on a latent image carrier by an electrostatic photography process is printed by transfer-printing on a transfer-printing sheet and a toner collected from the latent image carrier after cleaning thereof is performed is conveyed and discharged to the outside.
In an electrostatic recording apparatus in which a toner image formed by an electrostatic photography process on a latent image carrier, such as a photosensitive member, is printed on a transfer-printing sheet by transfer-printing, toner remaining on the surface of the latent image carrier after the toner image has been printed on a transfer-printing sheet is removed therefrom usually by means of a cleaning member, such as a cleaning roller having a fur brush attached to its surface or a cleaning blade and collected to toner receiver of a semi-circular cross section in its lower portion having a length substantially equal to the width of the latent image carrier which extends in a direction perpendicular to the direction of travel of the latent image carrier. The toner introduced into the toner receiver is discharged therefrom by a screw conveyor mounted in the toner receiver which extends along the entire length thereof. In electrostatic recording apparatus of this construction, the latent image carrier is usually a photosensitive member, so that the latent image carrier shall hereinafter be referred to as a photosensitive member.
A new type of electrostatic recording apparatus developed in recent years is constructed such that, to facilitate removal of transfer-printing sheets involved in a jam and maintenance of the apparatus, an upper unit of the apparatus including the photosensitive member and parts located thereabove, including the cleaning member and a collected toner coveying device composed of the toner receiver and the screw conveyor, tilts in a direction perpendicular to the direction in which the photosensitive member travels or in an axial direction of the screw conveyor referred to hereinabove and opens the transfer-printing sheet path.
In this type of electrostatic recording apparatus, when the apparatus is opened, the screw conveyor for discharging the toner tilts in an axial direction. If the screw conveyor is of the type which is formed by winding a spiral wire around a shaft of the screw conveyor with a gap therebetween, the toner in the toner receiver would move toward a portion thereof which is at a lower level through the gap between the spiral wire and the shaft as the toner receiver tilts upon the apparatus being opened. The toner moving toward the lower level might spill from the toner receiver at one end thereof lower than the other end thereof, thereby contaminating the photosensitive member and the transfer-printing coveying section.
When the screw conveyor is shaped like an auger in which spiral fins in contact with the semi-circular groove in the lower portion of the toner receiver are wound on the shaft of the screw conveyor with no gap therebetween, the phenomenon described hereinabove does not occur. However, when the recovered toner collected in the toner receiver exceeds a predetermined volume, the toner could slide over the upper portion of the screw conveyor and collect in the portion of the toner receiver which is at a lower level and might spill from the toner receiver.